Crystallisation of molecules, such as macromolecules, is an important technique for the biochemistry art. Biochemical molecules, such as nucleic acids, proteins and carbohydrates have unpredictable crystallisation structures, and often the 3D structure of the crystallized molecules play an important role for their biological functions. To get detailed knowledge about the way a protein functions it is critical to determine the three dimensional structure of the protein, since 3D structure and function are very tightly coupled. When biological processes need to be manipulated, the 3D structure is particularly useful, which is seen in medical research. Today more that 90% of the drugs on the market are small ligands that interact with a protein. To understand this interaction and to exploit it in the creation of new and improved drugs, the 3D structure of the ligand-protein complex has to be determined.
Crystallisation of molecules e.g. macromolecules, such as proteins is performed by providing a solution of the target compound, and altering the chemical environment of the dissolved target compound such that the target becomes less soluble and reverts to its solid form in crystalline form. This change in chemical environment is typically accomplished by introducing a precipitant that makes the target compound less soluble.
U.S. Pat. No. 6,409,832 describes a microfluidic device for promoting protein crystal growth using liquid-liquid diffusion. The device comprises one or more mixing and crystallisation chambers each comprising an inlet for a protein solution and an opposite inlet for a crystallization agent (precipitant). The protein solution is introduced via protein inlet into filling chambers with a specific volume, and there from it enters into the mixing chamber. The crystallization agent is filled via the crystallization agent inlets into the mixing chambers and the liquids are mixed using liquid-liquid diffusion.
US 2003/61687 discloses different microfluidic systems for use in high throughput screening of crystallization of a target material. The crystallisation is accomplished by introducing a solution of the target material into a plurality of chambers of a microfabricated fluidic device. The microfabricated fluidic device is then manipulated to vary the solution condition in the chambers, thereby simultaneously providing a large number of crystallization environments. The microfluidic system comprises an elastomeric block including the microfabricated chambers.
The system for crystallizing a target material comprises an elastomeric block including a microfabricated chamber configured to contain a volume of a solution of the target material, and a microfabricated flow channel in fluid communication with the chamber, the flow channel introducing a volume of a crystallizing agent into the chamber. The structure is manipulated to vary the solution condition in the chambers by deforming the elastomeric material to block fluid flow or to open for fluid flow or to metering an amount of fluid.
The crystallization system may further comprise an isolation structure configured to selectively isolate the chamber from the flow channel by deforming an elastomeric wall as the flow channel receives a volume of a crystallizing agent, and then to place the chamber into contact with the flow channel to alter a solution condition within the chamber. Alternatively, the crystallization system may further comprise a control channel overlying the chamber and separated from the chamber by a membrane, the membrane deflectable into the chamber to exclude a calibrated volume of sample solution from the chamber, such that relaxation of the membrane draws the calibrated volume of the crystallizing agent into the chamber. Further alternatively, the crystallization system may comprise a plurality of first parallel flow channels in fluid communication with a target material, and a plurality of second parallel flow channels orthogonal to and intersecting the first flow channels to create a plurality of junctions, the second flow channels in fluid communication with a crystallizing agent such that an array of solution environments can be created at the junctions.
WO 2004/067174 discloses an apparatus for performing microchemistry. The apparatus comprises a vapour permeable microfluidic chip channel structure with a supply conduit. The chip structure has first and second opposed ends to enable first and second fluid materials to interact by flowing the first and second fluid materials towards one another from the opposed ends of the supply conduit, and a valve mechanism in the chip structure operable to open and close the supply conduit at an intermediate position located between the first and second ends thereof whereby the chip structure is sequentially movable from a filling state in which the intermediate position is closed to enable the fluid materials to be blind-filled in the supply conduit on opposed sides of the intermediate position and an interaction state in which the intermediate position is open to enable the fluid materials to interact. The apparatus further comprises a vaporizer for forming a vaporous environment about the chip structure to compensate for evaporation of the fluid materials from the supply conduit of the chip structure in the interaction state.
US 2005/0205005 discloses a microfluidic structure for use in high throughput screening of protein crystallization. The microfluidic structure comprises a mixing chip allowing for precise metering of reagents to rapidly create a large number of potential crystallization. The microfluidic structure is of a micro machined elastomeric material having flow channels is several layers for providing a valve structure.
The objective of the invention is to provide a device for promoting crystallisation of target molecules, which device is simple and inexpensive to produce, and simple to operate.
The objective of the invention is also to provide a simple method for operating the device.
These objectives have been achieved by the invention as it is defined in the claims. And as it will be explained below, the invention and embodiments of the invention exhibit further beneficial properties compared with prior art crystallisation devices and methods.